Tachyon potential in KBc subalgebra

Understand

We evaluate the classical action and the effective tachyon potential of open string field theory within KBc subalgebra, which is extensively used in analytic solution for tachyon condensation recently found by Erler and Schnabl.

• It is found that the level expansion of the string field terminates at level 3.
• We find that the closed string vacuum is a saddle point of the classical action.
• We also evaluate the effective potential for tachyon field.